The present invention relates to a method and apparatus for classifying plain cigarettes or filter cigarettes of unit length or multiple unit length, cigars, cigarillos or cheroots with or without filters, filter tips or filter rod sections of unit length or multiple unit length, and analogous rod-shaped articles. More particularly, the invention relates to a method and apparatus for segregating defective and potentially defective rod-shaped articles from satisfactory articles while such articles are transported from a producing or making machine at a first station to a second station where the articles are subjected to one or more further treatments. The method and apparatus of the present invention can be employed with particular advantage for classification of plain cigarettes which travel from a cigarette rod machine to a filter cigarette machine.
The quality of cigarettes which are produced in a modern high-speed cigarette rod machine depends on operating conditions which prevail at the producing station. Such operating conditions can involve the speed at which the articles are produced. Also, the operating conditions can involve the operation of a trimming device which is usually employed in a cigarette rod machine to remove surplus tobacco from a tobacco stream and to thus convert the stream into a filler rod which is thereupon wrapped into cigarette paper to form a wrapped rod ready to be subdivided by a cutoff to yield sections or plain cigarettes of unit length of multiple unit length. If the cutting element or elements of the trimmer are improperly positioned or if the density of the stream varies, successive increments of the filler will contain different amounts of tobacco, i.e., the tobacco rod sections will be too light or too heavy. It is desirable to segregate from satisfactory cigarettes all such cigarettes which are clearly defective as well as all such cigarettes which are likely to be defective because they are produced when the operating conditions at the producing station are conducive to or indicative of the production of defective or potentially defective articles. The segregation is preferably completed before the cigarettes reach the next processing station because all work which is performed for further processing of defective cigarettes is wasted and such work might entail additional losses in valuable material, particularly when a defective cigarette rod section is united with a filter tip to form therewith a defective filter cigarette which must be ejected or otherwise segregated before it reaches the consumer.
British Patent No. 994,035 discloses a mechanical ejector device which is designed to expel reject cigarettes from a cigarette making machine. The ejector device is installed between the outlet of the cigarette making machine and a transfer drum and is set in operation whenever the machine is operated at less than normal speed. A drawback of such proposal is that the ejector device is likely to deform, change the orientation and/or otherwise affect the appearance, position or condition of the first cigarette which is intended to enter the transfer drum. The first cigarette is then likely to block the path of movement of next-following cigarettes and/or to interfere with proper operation of the processing machine which receives cigarettes from the transfer drum. This can cause substantial losses in output and/or damage to the processing machine.